Far removed from indie rock buzz bands, the folk duo Arborea have never seemed in a rush, but their fourth album, Red Planet, finds them more patient than ever, building music around their own slowly churning clockworks. Self-recording and self-producing again, largely in a cabin on a lake in Maine, Shanti and Buck Curran continue to expand their palette in subtly assertive ways. Clocking in at over 50 minutes, Red Planet is not only the longest Arborea outing yet, but -- in quiet ways -- also possesses the largest scope. The nine-and-a-half-minute "Wolves" gives the band its most sustained canvas yet, Shanti's voice doubled gently over frequent guest Helena Espvall's now familiar cello and Buck's pedal tones. The long tracks, and further use of Shanti's harmonium -- introduced on 2008's House of Sticks -- make for more slowly unfolding pieces than ever. More than ever, though, Shanti's vocals find their sources in traditional motifs and melodies, making for Arborea's most attractive batch of songs yet. "Black Is the Colour" builds on the familiar Celtic folk song, while "Careless Love" attaches itself with ghostly allusion to the blues song first recorded by Lonnie Johnson. Their cover of Tim Buckley's "Phantasmagoria in Two" finds a static peace until dramatically relieved by short electric guitar phrases and a buried tapestry of fine stringwork from Buck. "Spain," meanwhile, presents something more earthbound, of verses and refrains, though no less elegant. ~ Jesse Jarnow